One common misconception is that menstrual cups make you loose because their size is larger than tampons. Let’s break down why you don’t need to worry about this happening to you.
Understanding the Vagina
The vagina is purpose-built to stretch and return to its original size like a rubber band. This applies to the use of internal period products that temporarily push against the walls and “stretch” it, such as a menstrual cup. The principle remains true across other things going into the vagina that temporarily stretch it like a penis, toys, or fingers. The same applies to the vagina’s amazing elastic properties when a baby exits. Vaginas are badass.
The vagina is a muscle that can tighten and relax repeatedly. If you’re aroused it lengthens and the walls of the vagina soften to make penetration easier.
Origins of this Myth
The “loose vagina” myth stems from misogyny – plain and simple. Meant to shame a person who engages in sexual activities deemed more frequent than “acceptable,” saying someone has a loose vagina due to their sexual history has no basis in fact.
Related Article: Can Virgins Use Menstrual Cups?
Penis size vs Menstrual Cup size
The average girth of a penis is 4.6 inches (116 mm) in circumference. The average penis girth is 37.2 mm in diameter.
Menstrual cups are measured by the size of their opening at the top, typically the largest section across, in diameter. The average size of “large” cups measures 46 mm in diameter or 5.3 inches (144 mm) in circumference.
Some cups will have a smaller diameter than the average penis, some larger. And of course, some penises will be larger in girth (circumference) than any menstrual cup.
The point is, no matter their size, things will enter and exit the vagina without permanently loosening it. This is by design!
What causes the vagina to loosen?
Your vagina will probably loosen slightly but not because of your use of tampons, menstrual cups, your number/frequency of partners, or the size of toy you insert. Age and pregnancy are two things that will ultimately cause a small amount of loosening in your vagina.
Changes in your hormones as you age can affect your vagina’s elasticity. With age, your pelvic floor muscles can loosen.
A full-term pregnancy can loosen the pelvic floor. Delivering a baby vaginally is another aspect that might contribute (especially multiple deliveries and/or later in life deliveries).
Too loose or too tight?
If you’re concerned that you have abnormal vaginal laxity or that your vagina is too tight you should consult with a pelvic floor therapist. A loose pelvic floor can be addressed with exercise overseen by a PT. Exercising is addressing the muscles around the vagina, not the vagina itself. If you experience extreme tightness you may have a medical condition, such as vaginismus, also helped by treatment with a pelvic floor therapist.
Self-treatment and diagnosis are not advised and trying to simply “kegel” can do more harm than good if it’s not done correctly.
Find a licensed pelvic floor therapist near you.
Why menstrual cups are sized

No two vaginas are the same, they’re like snowflakes. We are born with different shapes and anatomies inside and out. Some people will need a smaller-sized menstrual cup for comfort and a better fit. That same person as they age or after pregnancy might find they then need a larger diameter menstrual cup for a leak-free experience. The guidelines for sizing menstrual cups are just that – guidelines. If you’re under 30 and find a larger cup that fits you better that is ok! Same if you’re over 40 and a size small works best. The menstrual cup quiz on Period Nirvana takes more into account than just your age and pregnancy history to match you to the right cup size and shape for you.
Picking the right menstrual cup size comes down to many factors but long-term use of cups does not lead one to need a larger size cup down the line. Using a larger cup will also not mean that you can’t switch to a smaller one later on if that fits better.
Bottomline?
Using menstrual cups will not stretch out your vagina or make you loose.
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